Technical Field
The present invention relates to cross-linked tetrapolymers. More specifically, the present invention relates to cross-linked tetrapolymers containing polymerized units of at least four different diallyl quaternary ammonium salt monomers, methods of preparing the tetrapolymers and a method of removing metal ions from an aqueous solution by adsorbing the metal ions with the tetrapolymers.
Description of the Related Art
The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present invention.
With the increase of industrial activities, metal pollution may cause destructive environmental and health problems. Therefore, many approaches have been reported for the development of more effective technologies for wastewater treatment such as chemical precipitation, liquid extraction, electrodialysis, etc. [Fenglian Fu, Qi Wang, Removal of heavy metal ions from wastewaters: A review, Journal of Environmental Management 92 (2011) 407-418, Tokuyama, H., Hisaeda, J., Nii, S., Sakohara, S., Removal of heavy metal ions and humic acid from aqueous solutions by co-adsorption onto thermosensitive polymers. Sep. Purif. Technol. 71, (2010) 83-88—each incorporated herein by reference in its entirety]. Among these technologies, adsorption is considered as an efficient method for removal of pollutants in the wastewater treatment. However, the adsorption efficiency depends significantly on the nature of the adsorbent used. Numerous materials have been reported as adsorbents and classified to natural and synthetic adsorbents [George Z. Kyzas and Margaritis Kostoglou, Green Adsorbents for Wastewaters: A Critical Review, Materials 7 (2014) 333-364—incorporated herein by reference in its entirety]. However, these adsorbents have the disadvantages of low capacity, slow adsorption rate or poor recovery [Jia-Qian Jiang, S M Ashekuzzaman, Development of novel inorganic adsorbent for water treatment, Current Opinion in Chemical Engineering, 1, 2, (2012) 191-199—incorporated herein by reference in its entirety]. Thus, the design of effective materials, including organic, inorganic and nano-scale materials, as adsorbent is highly required by water treatment agencies [Mya Mya Khin, A. Sreekumaran Nair, V. Jagadeesh Babu, Rajendiran Murugan and Seeram Ramakrishna, A review on nanomaterials for environmental remediation, Energy Environ. Sci., 2012, 5, 8075-8109; Clement Sanchez, Philippe Belleville, Michael Popall and Lionel Nicole, Applications of advanced hybrid organic-inorganic nanomaterials: from laboratory to market, Chem. Soc. Rev., 2011, 40, 696-753—each incorporated herein by reference in its entirety].
Chromium, Cr (III) is considered a metal that is toxic to the environment and several adsorbents have been reported for its removal from wastewaters. Adsorbents such as activated carbon, synthesized zeolite, diatomite, chitosan and poly(vinyl alcohol) have been reported [Schneider, R. M., Cavalin, C. F., Barros, S. D. Adsorption of chromium ions in activated carbon. Chemical Engineering Journal, 132, (2007) 355-362; Wu, D. Y., Sui, Y. M., He, S. B., Wang, X. Z., Li, C. J., Kong, H. N., Removal of trivalent chromium from aqueous solutions by zeolite synthesized from coal fly ash. Journal of Hazardous Materials, 155, (2008) 415-423; Guru, M., Venedik, D., & Murathan, A. Removal of trivalent chromium from water using low-cost natural diatomite. Journal of Hazardous Materials, 160, (2008) 318-323; Debasish Das, M. K., Sureshkumar, K., Radhakrishnan, J., Adsorptive removal of Cr(III) from aqueous solutions using tripolyphosphate cross-linked chitosan beads. Journal of Radioanalytical and Nuclear Chemistry, 289, (2011) 275-285; Xiao Jun Zuo, Rajasekhar Balasubramanian, Evaluation of a novel chitosan polymer-based adsorbent for the removal of chromium (III) in aqueous solutions, Carbohydrate Polymers, 92, 2, (2013) 2181-2186—each incorporated herein by reference in its entirety]. However, such adsorbents have the disadvantages of long equilibrium time and low capacity. Therefore, tailoring of materials with high capacity in less time is a challenge in water treatment. Polymers are considered good candidates due to the possibility of creating active motifs on their chains and thus more feasibility for higher uptake.
In view of the foregoing, there exists a need for novel materials and compositions with high adsorption capacity for chromium and advantageously, a range of other metals, over a short equilibrium time.